Joseph benjamin freeman



' together in suitable proportions and submit- UNITED STATES PATENT OFFICEO JOSEPH BENJAMIN FREEMAN, OF BATTERSEA, COUNTY OF SURREY,

ENGLAND.

WHITE PIGM ENT'.

SPECIFICATION forming part of Letters Patent No. 375,060, dated December 20, 1887.

Application filed April 2, 1886. Serial No. 200,382. (Specimens) Patented in England November 13, 1885, No. 18,891; in France February 12, 1886, No. 174,125,- in Belgium February 13, 1886, No. 71,968; in Italy March 31, 1886,l\'o. 19,584 in Austria Hungary November 29, 1886, No. 12,523 and No. 60,528, and in Canada February 26, 1887, No. 26,070.

To all whom it may concern:

Be it known that I, JosEPH BENJAMIN FREEMAN, a subject of the Queen of Great Britain, residing at Battersea, in the county of Surrey, England, have invented a new and useful Improvement in Vhite Pigments, (for which I have obtained Letters Patentof Great Britain, No. 13,891, dated November 13,1885; in France, No. 174,125, dated February 12, 1886; in Belgium, No. 71,968, dated February 13, 1886; in Austria-Hungary, No. 22,523 and No. 60,528, dated November 29, 1886 in Italy, No. 19,584, dated March 31, 1886, and in Canada, No. 26,070, dated February 26, 1887,) ofwhich the following is a specification.

This invention relates to a new white pigment which, when ground with oil in the customary way, forms a paint equal in body, opacity, or covering property to the best white lead produced by the Dutch method, and superior to it in color, durability, and density. The new pigment, moreover, possesses little or no smell, and is innoxious or non-poisonous.

This new white pigment consists in a composition of lead sulphate, zinc-white, and barium sulphate. These materials are mixed ted to great pressure and friction by grinding the mixture (preferably when in a dry state) under ordinary edge-ruuners, or otherwise. Under the term zinc-white I would have it understood that I include either zinc oxide or zinc sulphide, or a mixture of the two in any proportions, as both these substances are designated zinc-white in commerce.

By grinding zinc-white and lead sulphate together in the manner described, the particles of the lead and zinc compounds become incorporated together in a remarkable mannor, an entire change being produced in their character, and by the addition to the lead and zinccompounds of the barium sulphate the change of character above referred to is very greatly intensified, a pigment of equal,

if not of even greater, density of body and opacity than the lead and zinc compounds only being produced. The incorporation, in the manner herein described, of the barium sulphate with the lead and zinc compounds has, besides the effect of enhancing the covering properties of the pigment, the further and altogether distinct result of imparting to the paint considerably-greater freedom in working-that is to say, the paint leaves the brush much more easily and the painter is consequently enabled to employ much finer brushes and to produce a much smoother surface, free from brush-marks.

The proportions which I prefer to use are as follows: five parts, by weight, of lead sulphate; two parts, by weight, of zinc-white; one part, by weight, of barium sulphate. These proportions may, however, be considerably varied without changing the character of the pigment.

The ingredients are mixed and then ground together in a dry state under an ordinary edgerunner mill. The length of time during which the ingredients should be submitted to the grinding operation will vary according to the quantity of material treated, the weight of the edge-runners, and the speed of the mill, so that no definite time can be stated; but to insure the best results the mixture (of which the density before grinding was about one hundred and twelve (112) pounds to the cubic foot) should be ground until it acquires a density or" about two hundred (200) pounds to the cubic foot. This, under ordinary circumstances, will take from onequarter to one-half of an hour. When thoroughly incorporated by the grinding and pressure, the product is ready to be ground with oil in the customary way to form apaint.

The lead sulphate may be produced direct from metallic lead by submitting small feathers or flakes of metallic lead to the alternate action of dilute acetic acid and of atmospheric air, whereby a solution of lead acetate is produced, to which sulphuric acid is added phate, zinc white, and barium sulphate, in to precipitate the lead as sulphate. Although about the proportions substantially as herein :0

I prefer to use lead sulphate produced in this specified. manner, such mode of production constitutes 7 JOSEPH BENJAMIN FREEMAN. 5 no part of my invention. Witnesses:

What I claim asmy invention,and desire to GEO. J. B. FRANKLIN, secure by Letters Patent, is- J. WV. DEAN,

A white pigment composed of lead sul- Both of N0. 17 Gracechm'ch Street, London. 

